immigration in the news and a declaration from president obama, that it is time to take big steps to address the 11 million undocumented immigrants in america tonight. Abc's reena ninan now on what the president did today. Reporter: They are america's newest citizens. More than 4,400, sworn in today in southern california. While in nevada -- the time is now. Reporter: President obama unveiled his plan to get america's 11 million immigrants a big step closer to taking that oath. Yes, they broke the rules. They crossed the border illegally. But these 11 million men and women are now here. Reporter: The president's proposal calls for a path to citizenship. A process that includes passing a background check, paying taxes, paying a penalty, learning english and then going to the back of the line behind all the folks who are trying to come here legally. Reporter: And with that, a direct challenge to washington. And if congress is unable to move forward in a timely fashion, I will send up a bill based on my proposal and insist that they vote on it right away. Reporter: Listen again -- I will send up a bill -- Reporter: The president is pledging to put his political muscle behind this. Still, republicans insist tighter border security must happen before any movement on citiz citizenship. We've got very fundamental questions of lawfulness. Do we have a system that will stop the continued flow of people into the country? Reporter: The president today predicting this debate will become increasingly emotional. But he says the time has come for those 11 million people to come out of the shadows. Reena ninan, abc news, the white house. And a note now about the numbers that we're dealing with. Out of 11 million undocumented adults, 35% have been here for 15 years or longer. The median age, by the way, of an undocumented adult immigrant is 36 years old. And between 50% and 75% pay federal, state and local taxes.

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Immigration Changes on the Way

Millions of undocumented immigrants living in the U.S. may now have path to citizenship.